Load Bearing - Building & Construction - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Building & Construction

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 01-25-2014, 02:42 PM   #1
GLK
Newbie
 
Join Date: Jan 2014
Posts: 1
Rewards Points: 10
Default

load bearing


How much weight (at the middle) will an 11 ' douglas fir 4X4 carry? Supported at the ends.

Advertisement

GLK is offline   Reply With Quote
Old 01-25-2014, 11:44 PM   #2
Residential Designer
 
AndyGump's Avatar
 
Join Date: Sep 2010
Location: Orange County CA.
Posts: 1,317
Rewards Points: 550
Send a message via Skype™ to AndyGump
Default

load bearing


Maybe one child on a swing.

Andy.

Advertisement

__________________
Residential Drafter/Designer
www.draftinginoc.com
AndyGump is offline   Reply With Quote
Old 01-26-2014, 09:32 AM   #3
Member
 
Join Date: Apr 2012
Location: UK
Posts: 713
Rewards Points: 500
Default

load bearing


Depends how much deflection you are prepared to tolerate.
tony.g is offline   Reply With Quote
Old 01-26-2014, 10:12 AM   #4
Civil Engineer
 
Join Date: Mar 2009
Location: Boston
Posts: 4,300
Rewards Points: 2,178
Default

load bearing


According the the Forestry Forum (http://www.forestryforum.com/members/donp/Fblist.htm), douglas fir has an allowable maximum fiber bending stress ranging from 875 psi for #2 to 1850 psi for dense select structural. Let's take the worst and the best case for you. Assume that your 4x4 is actually 3.5 inches by 3.5 inches.

Worst Case 875psi: 190 lbs at the midpoint
Best case 1850 psi: 400 lbs

These values provide a factor of safety of 1.0 in bending. This does NOT analyze for deflection, which may be important in your case. This does NOT analyze for shear, which may be important. This analyzes for a STATIC load only, does NOT account for dynamic loads such as a swinging load. This does NOT account for repetitive loading or fatigue, which may be important in your case.
Daniel Holzman is online now   Reply With Quote
The Following User Says Thank You to Daniel Holzman For This Useful Post:
Old 01-28-2014, 08:53 AM   #5
General Contractor
 
Gary Evans's Avatar
 
Join Date: Jan 2014
Location: B.C. - Canada
Posts: 110
Rewards Points: 75
Default

load bearing


Those are some good numbers Daniel.......good to know.

What's important to GLK is the weight this will support at mid span..........I'd stick to the lower half...........200 - 300 lbs.
Provided there's not a big knot anywhere near the mid span, which could weaken the 4x4 a lot.
If this is a dynamic load ( a swing for instance) what's your best guess Daniel for reducing that weight rating ?

Also I think deflection is more of a concern than shear.......providing there's proper bearing support at the ends.......at least 2" .......3" would be better.

Last edited by Gary Evans; 01-28-2014 at 08:57 AM.
Gary Evans is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Beam for Load Bearing Wall jstein69 Building & Construction 3 02-17-2012 06:26 PM
Removing Kitchen Soffit - load bearing?? adrien2 Carpentry 4 09-25-2011 07:29 PM
Determining a Load Bearing Wall (Pic Included) Evil Scotsman General DIY Discussions 18 03-02-2011 03:46 PM
Can't tell what to do with this wall, load bearing?? fox_forma Building & Construction 22 09-26-2009 06:31 PM
Load bearing wall in basement Ezekiel Building & Construction 3 11-12-2008 10:23 PM




Top of Page | View New Posts